Scientists have discovered a new fly so small that it's tinier than a
grain of salt. But small size ain't the only weird thing about the tiny
phorid fly Euryplatea nanaknihali: it lives inside the decapitated
head of ants.

The flies lay their eggs in the body of the ant; the eggs develop
and migrate to the ant's head where they feed on the huge muscles used
to open and close the ant's mouthparts. They eventually devour the ant's
brain as well, causing it to wander aimlessly for two weeks. The head
then falls off after the fly larva dissolve the membrane that keeps
it attached.

The fly then takes up residence in the decapitated ant head for
another two weeks, before hatching out as a full-grown adult. In this
case, researchers think the fly parasitizes tiny acrobat ants, whose
heads are about as large as the fly itself and grow to about 0.16 inches
(4 millimeters) long.